Heterosis And Ralative Characters Analysis Of The Combinations With Genic Male-sterile Cotton Line GA18

As a sort of economical plants, the cotton, which is the main source of fibre, plays a essential role in the global economy. This makes us believe that it is quite important to select and cultivate new cotton varieties with higher yield and better fiber quality. It is a common way to make use of the heterosis to increase the crop yield, improve quality and increase their resistance. The result shows that the advantage of the heterosis is obvious, and recessive genic male sterile lines is used mostly in this domain at present.In this paper, there is a interpretion of the result of the cross combination, which is made by The new Genetic-male-sterility(GMS) line with transgenic insect-resistant cotton GA18 as female parent and crossed with 22 different cotton cultivars as male parents, and analyse the heterosis of yield and quality traits, characters correlation, and cluster analysis. Discussion about insect-resistant GMS lines and its hybrid correlations between the traits for yield characters and fiber quality, can provide reference for Breeding and Utilizing of nuclear male-sterile line in cotton.1,cytological observation: By culture of medium, dyeing and microscopic observation, a significant difference had been found between the fertile plant and sterile plant of GA18 on the pollen activity. The pollen germination rate is 53.13% in the fertile plant and only 4.35% in the sterile plant. The pollen germination rate of hybrid combination is much higher than the parents GA18. The paraffin method was used to detect the information of pollen abortion. The result showed that the anther development in the fertile plant was early than in the sterile plant and the earliest sterility was 6 days after the floral bud emergence.2,The heterosis analysis of yield and quality traits for crossing Parents and their hybrid F₁: According to research and analysis about 22 upland cotton varieties involving their yield characters and fiber quality of hybrid F₁, and the results shows that female parent GA18 is superior to 22 male parent of average about boll size and lint percentage. On the other hand, fiber quality, up half average length, fiber uniformity index, micronaire value, fiber elongation and fibre specific breaking strength are all slightly lower than the average in male parent. In the F₁ hybrid of heterosis in each traits, that nearly all traits of mid-parent heterosis, transgressive heterosis and competitive heterosis showed positive heterosis about hybrid combination except for most lint percentage behave negative values. Among factors of yield forms, the boll weight has a visible heterosis, but also there exists obvious differences among the groups. There is less heterosis in lint percentage, only 3 combinations were positive value on mid-parent heterosis and all below 5%. In the fiber quality, it showed positive heterosis on the mid-parent heterosis of fiber up half average length, and the majority of micronair value was demonstrated by negative heterosis, which means that the most cross combinations prepared by use of GA18 are better than parents in fiber fineness. At the same time, the fiber uniformity and elongation of heterosis is not obvious, and the data of the fiber uniformity of the 22 combinations is no more than 5% in mid-parent heterosis, transgressive heterosis and competitive heterosis. Furthermore, when parents and mean value of the parents have little difference, the heterosis of hybrid is closer to each other.3,Correlation analysis of characters: Based on the datas, the results of analysis of crossing parents traits, showed as followed. The fiber up half average length was positively and significantly correlative with fiber elongation and fibre specific breaking strength, but negative with boll weight and lint percentage. Micronaire was very significantly correlative with lint percentage, but did not show significant correlation with other traits. The fibre specific breaking strength was also significantly correlative with fiber elongation, and presented significantly negative correlation with boll weight and lint percentage. Besides that, there is negative or no correlation between boll weight and most of any other characters, but only shows positive correlation with lint percentage. The analysis of correlation between hybrid combinations shows that the fiber up half average length was significantly positive correlative with fibre specific breaking strength, fiber elongation and fiber uniformity index; but negative or significant negative with micronair, boll weight and lint percentage. And there is significantly positive correlation between fibre specific breaking strength and fiber uniformity index or fiber elongation, but shows very significantly negative correlation with boll weight and lint percentage. Furthermore, the same as the parents showed, there is a good positive correlation between boll weight and lint percentag.4,Cluster Analysis: Using DPS software for systems clustering analysis, when the distance is 12.71, the 23 parent samples could be classified as four major categories. Two low lint percentages of those materials was for the first category I ; 12 materials showed a higher lint percentage, boll, and fiber quality were for the general class II; the type III , including eight materials, such as No.08R196, was characterized by good fiber quality, lint percentage and boll weight in general; and the 08R191 was independent to the type IV . When carried out cluster analyses for 22 hybrid combinations and controls, 23 samples could be divided into three categories when the distance is 8.5 . The type I includes eight combinations, was characterized by good fiber quality, higher boll weight and lint percentage in general.08VH01, ck and other 12 combinations showed generally fiber quality, a higher lint percentage and boll formed the class II, and the fibre specific breaking strength average value is 29.0cN/Tex, average of fiber up half average length is 31.0mm, micronaire is 4.2,lint percentage is 40.8% and average of boll weight is 7.4g. The category III includes the material, 08H31 and 08H42, of which characters are excellent fiber quality, low lint percentage and boll weight.5,Screening SSR markers and Stability Analysis: there is only 45 pairs of polymorphism primers were found by using 1296 pair s of SSR primers, and 96.5% of SSR markers failed to amplify polymorphic bands. In the research, the SSR markers showed low-frequency polymorphism between parents, and SSR polymorphism primers is only 3.5%.